Gear trains are widely used for transmission of rotational motion in a variety of applications including engine systems. However, significant noise may result from impacting, and clattering gear teeth of adjacent gears in a gear train. Generally, the noise is generated when gear teeth of adjacent gears come out of mesh and are then forced back into mesh, e.g., when a tooth on a first gear comes out of mesh by moving forward more quickly than an adjacent tooth on a second gear and then having the tooth on the first gear impacts the adjacent tooth on the second gear. Noises generated from the gear train not only make the environment uncomfortable, the impacts between gear teeth also result in premature wear of the gear train.
U.S. Pat. No. 6,247,377 (the '377 patent) discloses a scissor gear assembly to minimize the noise generated in gear trains. The scissor gear assembly, as described in the '377 patent, includes a first gear with first teeth, and a second gear with second teeth corresponding to the first teeth of the first gear. The first gear and the second gear are co-axially positioned and adapted to rotate relative to each other. Further, a plurality of springs are positioned between the first gear and the second gear in a tangential direction, which provides a spring bias force to rotate the first and second gears relative to each other and change the alignment of the first teeth and the second teeth. The first teeth and the second teeth operate together as composite teeth with a variable effective teeth thickness. The composite teeth reduce or effectively eliminate a gap while meshing with an adjacent gear and as a result reduce noise.